Abstract: In order to make full use of the “temperature glide” of zeotropic mixtures in the evaporator, and avoid the adverse effects of the "component shift " in the condenser. An ORC system with separation, compression and remixing of zeotropic mixtures (SCRM-ORC) is proposed in the paper. Zeotropic mixtures are separated into two pure fluids by a partial condenser, and they enter different spaces of gas-liquid heat exchanger respectively for gas-liquid heat exchange. Then the pure fluids are compressed, mixed and reused. Using 120℃ geothermal water as heat source, R134a/R245fa as working fluid, thermodynamic, economic, and environmental models are established to analyze the effects of mass fraction of R134a on comprehensive performances of SCRM-ORC system, and then they are compared with CR-ORC system using R134a. Multi-objective optimization using genetic algorithm is performed to reveal the optimal performance and operating parameters of the system. The results show that compared with the CR-ORC system, the SCRM-ORC system can effectively reduce the release of condensation heat, and improve the recovery of condensation heat when the mass fraction of R134a is low, and it has better comprehensive performance. The partial condenser and gas-liquid heat exchanger are considered as a whole to compare with the novel condenser in the CR-ORC system, the sums of the two exergy losses and the investment costs are still smaller than those of the condenser in the CR-ORC system. When the mass fraction of R134a is 0.2181, the comprehensive performance of the system is optimal, the net output power is 3412.1kW, the investment payback period is 2.237 years, and the annual equivalent CO₂ emission reduction is 4520.6×10³ kg.